76
Alarm 64 — Loss of Communication with Energy Manage-
ment Module Board (Co.03)
Criteria for Trip
— The criterion is tested whether the unit is
ON or OFF and when a function that requires the Energy
Management Module (EMM) is configured. If communication
with the EMM is lost for a period of 10 seconds, the alarm will
be triggered.
Action to be Taken
— If any function controlled by the EMM
(3-Step and 4-20 mA Demand Limit, 4-20 mA and Space
Temperature Reset, Occupancy Override, and Ice Build) is
active, that function will be terminated. If an EMM function is
programmed, and communication is lost, the function will not
be allowed to start.
Reset Method
— Automatic, if communication is established,
the functions will be enabled.
Possible Causes
— If this condition is encountered, check the
following items:
• The EMM is installed, (
EMM NRCP2 Board
, EMM
). If
EMM NRCP2 Board
, EMM
=
YES
, then check for a con-
trol option that requires the EMM that may be enabled (cor-
rect configuration if not correct).
• power supply to EMM
• address of the EMM
• local equipment network (LEN) wiring
• confirm unit configuration to be sure that no options that
require the EMM are enabled
Alarm 66 — Loss of Communication with AUX Board 6
(Co.05)
Criteria for Trip
— The alarm criteria are checked whether the
unit is ON or OFF. If units are configured for minimum load
control or head pressure control (
Hot Gas Bypass Select
,
HGBP
=
Yes or Condenser Valve Select,
CON.V
=Yes
). If
communication with the AUX board is lost then the alarm will
be generated.
Action to be Taken
— Unit shut down or not allowed to start.
Reset Method
— Automatic, if communication is established,
the unit will start normally.
Possible Causes
— If this condition is encountered, check the
following items:
• power supply to the MLV/COND board
• address of the MLV/COND board
• local equipment network (LEN) wiring
• confirm network configuration
Alarm 67 — Cooler Freeze Protection (P.01)
Criteria for Trip
— The alarm criteria are checked whether the
unit is ON or OFF. If the entering or leaving water thermistor
senses a temperature at the freeze point or less, the alarm will
be generated. For a fresh water system (
Cooler Fluid Type
,
FLUD
=
1
), the freeze point is 34 F (1.1 C). For medium tem-
perature brine systems (
Cooler Fluid Type
, FLUD
=
2
), the
freeze point is Brine Freeze Set Point (
Brine Freeze Setpoint
,
LOSP
).
Action to be Taken
— Unit shut down or not allowed to start.
Chilled water pump will be started.
Reset Method
— Automatic, first occurrence in 24 hours if
LWT rises to 6° F (3° C) above set point. Manual, if more than
one occurrence in 24 hours.
Possible Causes
— If this condition is encountered, check the
following items:
• entering and leaving fluid thermistors for accuracy
• water flow rate
• loop volume — low loop volume at nominal flow rates can
in extreme cases bypass cold water to the cooler
• freezing conditions
• freeze protection items for proper operation
• glycol concentration and adjust
LOSP
accordingly
• If the Leaving Water Set Point is above 40 F (4.4 C) and
there is glycol in the loop, consider using the Medium
Temperature Brine option (
Cooler Fluid Type
, FLUD
=
2
)
to utilize the brine freeze point instead of 34 F (1.1 C)
Condenser Freeze Protection
Alarm 68 — Circuit A (P.02)
Alarm 69 — Circuit B (P.03)
NOTE: Alarms 53-55 are not used or supported. If this condi-
tion is encountered, confirm machine configuration.
Low Saturated Suction Temperature
Alarm 71 — Circuit A (P.05)
Alarm 72 — Circuit B (P.06)
Criteria for Trip
— The criteria are tested only when the
circuit is ON. This alarm is generated if one of the following
criteria is met:
• If the circuit Saturated Suction Temperature is below –13 F
(–25 C) for more than 30 seconds or 40 seconds if OAT is
less than 14 F (–10 C) or LWT is less than 36 F (2.2 C).
• If the circuit Saturated Suction Temperature is below –22 F
(–30 C) for more than 10 seconds, or 20 seconds if OAT less
than 50 F (10 C).
Action to be Taken
— The circuit is shut down immediately.
Prior to the alarm trip, the control will take action to avoid
the alarm. See Operating Modes 21 and 22 on page 54.
Reset Method
— Automatic, first occurrence in 24 hours.
Manual, if more than one occurrence in 24 hours.
Possible Causes
— If this condition is encountered, check the
following items:
• sensor wiring to Main Base Board
• board for a faulty channel
• faulty suction transducer
• cooler water flow
• loop volume
• EXV operation
• liquid line refrigerant restriction, filter drier, service valve,
etc
• refrigerant charge
• If the Leaving Water Set Point is above 40 F (4.4 C) and
there is glycol in the loop, consider using the Medium
Temperature Brine option (
Cooler Fluid Type
, FLUD
=
2
)
to utilize the brine freeze point instead of 34 F (1.1 C).
High Suction Superheat
Alarm 74 — Circuit A (P.08)
Alarm 75 — Circuit B (P.09)
Criteria for Trip
— The criteria are tested only when the cir-
cuit is ON. This alarm is generated if
all
of the following crite-
ria are met:
• The EXV position is equal to or greater than 98%.
• The circuit’s Suction Superheat (Suction Gas Temperature –
Saturated Suction Temperature) is greater than the super-
heat control set point.
• The circuit’s Saturated Suction Temperature is less than
Maximum Operating Pressure (MOP) set point (
EXV
MOP Setpoint
, MOP
) for more than 5 minutes.
Action to be Taken
— The circuit is shut down normally.
Reset Method
— Manual.
Possible Causes
— If this condition is encountered, check the
following items:
• suction pressure transducer wiring to Main Base Board
• board for a faulty channel
• a faulty suction transducer
• suction gas thermistor wiring to EXV Board 1 or to EXV
Board 2
• suction gas thermistor sensor for accuracy
• for EXV Board 1 or EXV Board 2 faulty channel
• EXV operation
